The blog of ObiterJ - responsible and sometimes critical comment on legal matters of general interest. This blog does not offer legal advice and should not be used as a substitute for professional legal advice.
'The life of the law has not been logic; it has been experience. The law embodies the story of a nation's development...it cannot be dealt with as if it contained the axioms and corollaries of a book of mathematics' - (Oliver Wendell Holmes - 1841 to 1935). Pro Aequitate Dicere

The European Communities Act 1972 (ECA) is the legislation by which Parliament enabled law made by the European Union (EU) to apply within the United Kingdom. In the Miller judgment, adopting an analysis by Professor Finnis, the Supreme Court referred to the ECA as the 'conduit pipe' by which EU law is introduced into UK domestic law (para 65) and - "So long as the 1972 Act remains in force, its effect is to constitute EU law an independent and overriding source of domestic law."

Clause 1 will remove EU law from its position as a source of domestic law. Removing the ECA will necessitate dealing with the vast amount of law which has emanated from the EU and flowed into the UK via the "conduit pipe." Unless this is done, there would be a legal vacuum in numerous areas.

Important
note:

Clause 1, if enacted, will
hand to Ministers the right to determine the exact date on which the European
Communities Act 1972 will be repealed and, in doing so, bring to an end the
legal methods by which EU law enters
into the domestic law.Clause 1 does not
reserve to Parliament any power to consider whether to accept or reject the Minister’s
chosen date.

Exit Day:

The ECA will be repealed on "exit day." One might be forgiven for thinking that, as things currently stand, this is to be 29th March 2019. That is, the end of the 2 year period referred to in Article 50 of the Treaty on European Union. It may not be so simple! Let's turn to Clause 14(1) where we are told that:

“exit day” means such day as a Minister of the Crown may by
regulations appoint (and see subsection (2));

1) Schedule 7 paragraph 16 that -
"Any power of a Minister of the Crown under this Act to appoint a day
includes a power to appoint a time on that day if the Minister considers
it appropriate to do so."

Returning to Clause 14 we see that Clause 14(2) says: In this
Act - (a)where a Minister of the
Crown appoints a time as well as a day as exit day (see paragraph 16 of Schedule 7), references to before,
after or on that day, or to beginning with that day, are accordingly to
be read as references to before, after or at that time on that day or
(as the case maybe) to beginning with that time on that day, and (b)where a Minister of the
Crown does not appoint a time as well as a day as exit day, the reference to exit day in section 1 is to be
read as a reference to the beginning of that day.

2) The term Minister of the Crown is defined in Clause 14(1) as having the same meaning as in the
Ministers of the Crown Act 1975 and also includes the
Commissioners for Her Majesty's Revenue and Customs. Basically, Ministers of the Crown are those who hold an office in "Her Majesty’s Government in the United
Kingdom."

The importance of "Exit Day"

"Exit day" is used throughout the Bill. To take just one
example, Clause 2(1) states: "EU-derived domestic legislation, as it has
effect in domestic law immediately before exit day, continues to have effect in
domestic law on and after exit day."

Reference back to Exit Day may continue for many years adding
complexity to the law. This will require some sort of record of the state of EU-derived domestic legislation on Exit Day and the record will be a baseline for the UK until things are changed by use of the extensive powers granted by the Bill to enable changes to be made. The Bill contains provision for such a record to be made - see Schedule
5 dealing with Publication of retained direct EU legislation etc.

Regulations:

A number of provisions in the Bill deal extensively with what Regulations may do and these will apply when a Minister makes regulations appointing Exit Day.

Clause
17(5)states - "A Minister of the Crown may by regulations
make such transitional, transitory or saving provision as the Minister
considers appropriate in connection with the coming into force of any provision
of this Act or the appointment of exit day."

Schedule 7 Part 3 General Provision about powers under the Act. Paragraph 13 of the Schedule:

Any power to make regulations under this Act -(a)may be exercised so as to - (i)modify retained EU law, or (ii)make different provision for different cases or descriptions of case, different circumstances, different purposes or different areas, and (b)includes power to make supplementary, incidental, consequential, transitional, transitory or saving provision (including provision re-stating any retained EU law in a clearer or more accessible way).

Summary:

The Bill therefore permits a Minister of the Crown to make regulations to appoint Exit Day - and the Minister may even specify a particular time on that day.

The thought occurred to me that, as there are many Ministers of the Crown, there is a possibility that different exit days might be appointed by different Ministers. Also, in appointing exit day, each Minister may see the need to specify a distinct set of transitional arrangements under Clause 17(5) or under Schedule 7 Part 3. Whilst this possibility may exist it is far from clear - at least to me - whether events will take this course because some clauses in the Bill appear to permit only one exit day including Clause 1 repealing the ECA on exit day. The repeal of the ECA is, of course, the political dream of those in favour of Brexit. It is also a step of huge constitutional and legal significance about which maximum clarity is surely desirable.